The present invention relates to orthodontic brackets specifically designed for use on the lingual side of the teeth.
Orthodontic brackets for use on the lingual (back) side of the teeth are generally known but have not found the wide application that standard, buccal-side mounted brackets have seen. One such bracket is described in FIGS. 18-21 of Creekmore U.S. Pat. No. 4,531,911. Creekmore teaches a single/twin orthodontic bracket with an elastic ligature member securing an edgewise archwire within the archwire slot of the bracket wherein the archwire slot and archwire are severely angulated position such as for lingual application. The Creekmore bracket has four separate tie wings and a complicated profile that makes it difficult to use and manufacture. The present invention provides an improves, simplified lingual bracket having an angles slot.
The invention provides an orthodontic bracket having a base portion configured for attachment to a mounting device such as a bonding pad that is directly secured to the tooth of a patient. A central portion of the bracket adjacent the base portion has a pair of sides that taper to a minimum diameter at a midline of the central portion, preferably giving the bracket an hourglass shape. A pair of single tie wings extend in gingival and occlusal directions respectively from the central portion, which tie wings define outer end portions that are wider than the central portion and have undersurfaces positioned for mounting archwire retaining bands therein. An outwardly opening archwire slot elongated in the mesial direction is formed in the central portion, which slot extends at an acute angle relative to an imaginary line extending in a buccal-lingual direction such that the slot opens closer to the gingival tie wing than the occlusal tie wing. An inner end portion of the occlusal tie wing overhangs the archwire slot. This bracket has a simple shape yet provides optimum interbracket distance as described hereafter, which distance is especially important when an orthodontic appliance using the bracket is to be mounted on the lingual side of the teeth where the curvature of the archwire is more severe.
Such a bracket may be used to form an orthodontic appliance according to the invention applied to the lingual side of a patient""s teeth. The appliance includes a number of such brackets each mounted to lingual surfaces of incisor or canine teeth of the patient, united by a mesial archwire positioned in the archwire slot of each bracket and retained therein by elastic bands mounted over the tie wings and securing the archwire to each bracket. These and other aspects of the invention are discussed further in the detailed description which follows.